Fuse



Oct. 24, 1939. l.. J. MOLNER 2,177,533

FUSE

Filed July 28, 1938 INVENTOR 02005 J/lfolne" TO'RNEY Patented Oct. Z4, 1939 UNITED STATES PATENT OFFlCE 8 Claims.

This invention relates to tamper proof devices adapted to prevent a wire or penny being inserted to bridge the contacts in a fuse holder when the fuse is blown.`

An object of this invention is to provide a tamper-proof device of this type which is simple, of few parts, inexpensive, and has the contacts protected.

Another object is to eliminate the necessity of a threaded metal holder,

A further object is to provide a holder and fuse receptacle in which the contacts are provided for butt engagement, one of them being yieldable to eliminate the necessity for expensive precision constructions.

Referring to the drawing: y

Fig. 1 is a longitudinal section through one embodiment of this invention.

Fig. 2 is a top plan view of the stationary support for the fuse receptacle, with parts broken away.

The removable fuse receptacle lll is supported by a holder comprising a base preferably of porcelain or other appropriate insulating material, having integrally formed therefrom an up-y standing generally circular wall I2.

Within wall I2, and substantially concentric thereto, is a knob or projection I3 which may or may not be of the same material as the base and which may or may not be integral therewith. In the drawing this projection I3 is shown as being formed separately from the base. Within the knob or projection, and below the surface thereof, is a central contact I 4 constituting one of the contacts with which the fuse receptacle engages. The other contact of the fuse holder is the substantially ring shaped portion I5 extending around the bottom of the projection I3 but within wall I2. This contact ring I5 is bent or raised at I6 and Ilia so that the greater part of the ring is adapted to be yieldably engaged by a complementary contact carried by the fuse receptacle. This contact ring is secured to the base by the screw ISb or in any other convenient manner. A terminal binding screw I'l is located on a projection from the contact ring I5 while the opposite terminal screw I8 is located on a conducting strip I9 in contact with the central terminal I4. As shown on the drawing, the lower central portion of the central conducting rod is threaded to receive a nut 20 for clamping the conductor strip I9 in position and at the same time clamping the knob or projection I3 on to the base. The projection I3 is shown in Fig. 1 as being recessed to allow inser- (Cl. 200e-119) tion of the nut prior to its being threaded on the central conducting rod.

The fuse receptacle includes a body of cup shaped insulating material having imbedded therein a spherical or other anchoring portion 2| for its central contact which is adapted to engage the central contact I4 of the fuse holder.

The central contact 2| is preferably of carbon and the contact I4 preferably of copper or other good electrical conducting metal, A fusible strip 22 extends from the contact 2| radially outward and then longitudinally within a passage i223 in. a side wall of the cup, being secured at its lower end portion to a Contact ring 24 which engages the contact ring I5. The contact ring 24 is preferably soldered to the fusible strip 22 when not inserted in the cup walls and after being soldered to the fusible strip is then set into the cup walls as shown in Fig. l, a plurality of pins 25 being used to firmly hold the contact ring 24 in place. As shown in Fig. l., the pins 25 extend from the cup walls and also through the contact ring 24. Across the opposite end of the cup is placed a sheet of mica or other substantially transparent covering asis customary in fuse receptacles in o-rder that observation may determine whether the fuse has been melted. A clamping band of metal 21 extends around the base of the cup for holding the mica or other transparent material in position.

The inside of the cup walls are threaded for cooperation with corresponding threads on the outside of the projection I3.

The cup I of the fuse receptacle may be of the same material as the projection I3 and base, though preferably it is of a molded resinous or phenolic condensation type product. The materials of the projection I3 and cup ID should be such as to allow smooth and easy threading of the one upon the other.

Among the advantages of this invention may be mentioned its simplicity and few parts. Neither the fuse receptacle nor its holder is apt to be injured by dropping since there is no threaded metal shell. The contacts of both parts are protected and surrounded by insulation so that there is no likelihood of shock and the device is substantially foolproof.

In inserting the fuse receptacle on to the holder the cup is rotated until the contact ring 24 first engages the contact ring I5 and nnally the circuit is closed by engagement of the contacts 2| and I4. In opening the circuit the contacts 2| and I4 separate in advance of the contacts 24 and I5. The contact I5 being yieldable takes care of any wear or corrosion in the contacts 2| and I4.

I claimf u l l l. A removable fuse receptacle, a holder therefor comprising a base and an encircling upstanding wall, a second and inner upstanding wall, contacts protected by said walls, at least one of said Walls constituting a guide for the removable receptacle, said removable receptacle being a cupshaped member of insulating material adapted to enclose the inner wall of the holder, contacts in the holder and receptacle adapted for butt engagement.

2. A holder for a removable fuse receptacle including inner and outer walls of insulating material, screw threads on the outer surface of the inner wall, a base connecting said Walls, a contact ring on the base between said walls, and another contact within the inner Wall extending to adjacent its top.

3. A removable fuse receptacle including a cupshaped member of insulating material having screw threads formed on the inner surface of the sides of the cup, a contact in the inner base of the cup, a second contact in the cup Walls remote from the base, a strip of fusible material connecting said contacts, and a cover of transparent material across the base of the cup to render the fusible strip visible.

4. The combination with a stationary fuse holder, of a removable fuse receptacle of the type adapted to prevent bridging the contacts within the stationary fuse holder, the improvement in said holder and receptacle which includes an upstanding projection of insulating material on said holder and having screw threads on the outer surface thereof, a contact within said projection, a yieldable ring contact on said holder around the base of said projection, the removable receptacle being cup-shaped, provided with threads on the inner surface of the cup Walls adapted to cooperate with the threads on said projection, a contact in the base of the cup for engagement with the contact in said projection, and another contact carried by and adjacent an end of the cup walls for engagement with said yieldable ring, and a fuse strip connecting the contacts of the removable receptacle.

5. A stationary member with which a fuse receptacle is adapted to contact, said member including a base, terminals on the base, an upstanding wall of insulating material, a knob oi' insulating material enclosed by the wall, a central contact in said knob, means clamping said knob to the base, a conductor between one of the base terminals and said central contact, said clamping means also holding said conductor and central contact in position.

6. A stationary member with which a fuse receptacle is adapted to contact, said member including a base, terminals on the base, an upstanding wall of insulating material, a knob of insulating material enclosed by the wall, a central Contact in said knob, a conductor intermediate the top and bottom of said base and connecting said central contact with one of the terminals on the base, a contact ring around the knob, within Said wall of insulating material, and connected to another base terminal.

7. A stationary member with which a fuse receptacle is adapted to contact, said member including a base, terminals on the base, an upstanding wall of insulating material, a knob of insulating material enclosed by the wall, a central contact in said knob, a conductor intermediate the top and bottom of said base and connecting said central contact with one of the terminals on the base, a contact ring around the knob, within Said wall of insulating material, and connected to another base terminal, said ring being bent so as to be yieldable and not lie contiguous the base in all portions thereof while yieldable.

8. A fuse receptacle of insulating material in cup form, a central contact embedded in and projecting from the base of said cup, a contact in the end portion of the cup walls, a fusible strip connecting the central and Wall contacts and extending in a passage between the inner and outer surfaces of the cup walls, said contact in the end 0f the cup walls being removable from the cup walls to enable it to be attached to said fusible strip, and means for holding said contact at least partially within the cup walls.

LOUIS J. MOLNER. 

